Refining mineral oils



April 27, 1943. G. s. BAYSJR.

` REFINING MINERAL oILs 2 Sheets-Sheet 1 Filed July 5, 1941 mzON April `27, 1943.

G.s. BAYs; JR RFINIG MINERAL OILS Filed July 5, 1941 2 Sheets-Sheet 2 Patented Apr. 27, 1943 REFINING MINERAL OILS George S. Bays, Jr.,lBaytown, Tex., assignor to Standard Oil Development Company, a corporation of Delaware Application July 5, 1941, Serial No'. 401,124

l1 Claims.

The present invention is concerned with the refining of mineral oils. The invention more particularly relates to the production of high yields of high quality petroleum oil products boiling in the lubricating oil boiling range. In accordance with the present process, lubricating oils are refined by contacting the same with a mineral acid, separating the mineral acid sludge, followed by treating the acid sludge with a liquefied normally gaseous hydrocarbon. under conditions to recover an additional amount of a high quality lubricating oil.

It is well known in the art to refine petroleum oils by various distillation, cracking, and related operations. For example, it is known in the art to remove objectionable sulfur compounds from lpetroleum oils, such as petroleum oils boiling in the lubricating oil boiling range, by contacting the same with mineral acids, particularly with a sulfuric acid. These oils are contacted under various temperature and pressure conditions which are adjusted to secure the desired removal 0f the objectionable constituents.Y While these operations are entirely satisfactory for the production of a high quality lubricating oil, they are objectionable i`n that a substantial amount of the oil is lost in the acid sludge. In order to overcome these inherent disadvantages, various suggestions have been made for recovering the oil from the acid sludge. However, in operations heretofore proposed the oil recovered from acid sludge was of an inferior quality and could not be readily utilized as a high quality oil.

I have, however, now discovered that providing a particular sequence and arrangement of stages be employed, it is possible to recover additional high quality oil from the acid sludge, which oil may be readily combined with the acid-treated oil product. In accordance with my process the acid sludge is removed and treated with an additional quantity of propane under conditions to remove from the acid sludge an appreciable quantity of high quality oil.

The process of my invention may be readily understood by reference to the attached drawings illustrating modifications of the same. Figure 1 illustrates an adaptation of my invention in which a single acid treating stage is employed, while Figure 2fillustrates a preferred adaptation utilizing two acid treating stages.

Referring specifically to Figure l, it is assumed for the purpose of illustration that the feed oil comprises a crude petroleum residuum having a gravity of about 20 A. P. I., and a Saybolt Universal viscosity `of about 450 seconds at 210 F. The feed oil is introduced into the system by means of line I. The feed oil is mixed with a quantity of liquid propane which is with'- drawn from propane storage 2 and introduced into line I by means of line 3. The propane oil mixture is passed through a mixing zone 4 and is introduced into settling zone 5 wherein precipitated asphaltic constituents amounting to about 25% of the feed oil are separated and removed by means of line 5.' The propane oil mixture is withdrawn from zone 5 by means of line l, and chilled and dewaxed if desirable in chilling and dewaxing zone 25. The waxy constituents are removed by means of line 26 while the dewaxed oil is removed by means of line 21. If the cil comprises a non-waxy oil, the same may by-pass Zone 25 by means of line 28. The oil is then mixed with a quantity of mineral acid which for the purpose `of description is taken to be a 98% sulfuric acid and is introduced into the system by means of line 8. The sulfuric acid is introduced into line 27 by means of line 8 and the mixture passed through mixing zone 9 and introduced into initial separation Azone Ill. Acid sludge is withdrawn from 'separation zone I0 by means of line II while the acid-treated propane oil mixture is removed by means of line I2. The desired level in initial separation Azone I0 is maintained by means of a control valve liquid level arrangement I3. The acid oil mixture withdrawn by means of line I2 is introduced into secondary separation zone IA wherein a final separation is made between acid sludge which is Withdrawn by means of line I5 and combined v with the acid sludge withdrawn by means of line II. The oil propane solution .is Withdrawn from secondary separation zone I4 by means ofline It and passed `to Aa propane recovery zone in which the propane is separated Afrom the treated cil. The level in zone I4 is maintained at the desired height by means of a control valve liquid level arrangement I 'I.

rIhe acid sludge removed from zone I0 and zone I i by means of line II and line I5, rrespectively, is mixed with an additional quantitypf liquid propane which is introduced by means of line I8. The propaneand acid sludge is passed through mixing zone I9 and introduced into a tertiary separation zone 20 wherein the'washed acid sludgefis separated and removedV by'means of line 2 I. The level in zone 20 is maintained by means of a control valve liquid levelarrangement 22. The propane oil solution which sepa? rates in zone 20 is preferablyvremoved Aby means of line 23 and combined with the oil solution removed from zone I4 by means of line I6. However, the propane oil solution removed by means of line 23 may be recycled to mixing zone 9 by means of lines 24 and 29.

Under certain conditions, however, the oil recovered from the acid sludge may also be withdrawn by means of line 24, and passed to propane recovery zone 30, wherein the propane is removed by means of line 3l and the propane-free oil by means of line 32. Although this oil may be withdrawn from the system, under certain conditions it may be recycled to mixing zone 9 by means of line 33. The washed acid sludge removed from zone 20 by means of line 2| is preferably passed to a propane recovery Zone wherein the propane is removed from the acid sludge and the acid regenerated.

Referring specifcally'to Figure 2, it is assumed that the feed oil comprises an oil similar to thatV The oil is ,5

described with respect to Figure 1. introduced into the system by means of line 49. The oil is mixed with a liquefied normally gaseous hydrocarbon, which for the purpose of description is taken to be liquefied propane, and which is withdrawn from propane storage zone 4I and introduced into line 40 by means of line 42. The mixture is passed to mixing zone 43 and then to a separation zone 44 wherein precipitated constituents may be separated and removed from the propane oil solution by means of line 45.

The mixture withdrawn from separation zone 44 may be passed through chilling and dewaxing zone 10 wherein the waxy constituents are removedV from the oil and separated by means of line 1|. If it is not desired to dewax the oil, the same may by-pass Zone 10 by means of line 12. The solution after removal from separation zone 44 or dewaxing zone 10 is mixed with a propane acid sludge solution secured as hereinafter described, which is introduced by means of line 41. The mixture is passed through mixing zone 46 and introduced into initial separation zone 48 wherein a separation is made between acid sludge and the propane oil solution. Acid sludge is withdrawn from zone 48 by means of line 49 and handled as hereinafter described. The propane oil solution is withdrawn from initial separation zone 48 by means of line 50 and combined with a mineral acid which for the purpose of description is taken to be a concentrated sulfuric acid. vThe sulfuric acid is introduced into line 50 by means of line l, the solution passed through mixing zone 52 and introduced into secondary separation zone 53 wherein a separation is made between acid sludge and the propane oil solution. The acid sludge is withdrawn from zone 53 by means of line 41 and combined with the feed solution passing to initial separation zone 48. The level in the respective zones 48 and 53 is maintained by means of control valve liquid level arrangements 54 and 55, respectively. The propane oil solution is removed from secondary separation zone 53 by means of line 56 and passed to a propane recovery zone wherein the propane is removed from the treated oil.

The acid sludge removed by means of line 49 is combined with additional propane which is introduced into line 49 by means of line 51. 'I'he mixture is passed through mixing zone 58 and introduced into tertiary separation Zone 59 wherein a separation is made between the acid sludge and recovered oil. The acid sludge is withdrawn from tertiary separation zone 59 by means of line 60 and preferably passed to a propane recovery zone wherein the propane is removed from the spent acid, which acid is preferably regenerated and recycled to the system. The recovered oil propane solution is removed from zone 59 by means of line 6I and is preferably combined with the solution removed from zone 53 by means of line 56. However, the oil may ybe recirculated to zone 45 by means of line 63 or to zone 52 by means of line 64. Under certain conditions it may be desirable to remove the recovered oil propane solution by means of line 62 and to handle the same in a manner to separate the propane and to recover the oil. This operation may be conducted by passing the solution to recovery zone 18 wherein the propane is separated and removed overhead by means of line 14. The propane-free oil is preferably removed from the system by means of line 15, but it may be recycled to either zone 45 or 52 by means of lines 1B and 11, respectively.

Theprocess of the present invention may be widely varied.V It is to be understood that the respective zones may comprise any suitable number and arrangement of units. VThe process may be adapted for recovering petroleum oils from any acid sludge. The invention, however, is particularly adapted for increasing the yields and recovering a high quality petroleum oil product from acid sludges securedin the acid treatment of petroleum oils boiling inthe lubricating oil boiling range. In general, these oils have Saybolt Universal viscosities of, from about 30 to about 650 seconds at 210 F., and have gravities in the range from about 15 to 30 A. P. I.

The present process maybe adapted for treating sludges derived from oils which Yhave been contacted with various types of numeral acids. The operation, however, is particularly suitable for processing petroleum oil sludges secured when treating a feed oil-with arsulfuric acid, particularly with a sulfuric acid having a concentration in the range above about Espeoially desirable results are secured when the acid treating operation comprises the use of a sulfuric acid having a concentration in the range from about to about 100%. The normally liquefied hydrocarbon solvent used may comprise propane, butane, ethane, or a mixture of these constituents. However, in general, it is preferred to use a solvent which comprises at least 75% of liquefied propane. The amount of solvent employed will vary'Y considerably depending upon the particular acid sludge being treated. It is preferred to add Afrom about 2.0 to about 6.0 volumes-of Vsolvent per volume of feed oil entering the acid treating equipmentand to contact the mixture with from about 5 to about '15 pounds of 98100% sulfuric acid per barrel of solventfree oil. The acid sludge which separates is then preferably contacted with an additional 0.5 to 2.0 volumes of solvent per volume of sludge.

The contacting operation Ais'conducted at a pressure sufficient to maintain -the l,constituents in the liquid phase. `In general, the temperatures are in the range from about 40 F. to about F.v Preferred temperatures are in the range from about 85 F. to 105 F. A particularly preferrd operation comprises utilizing three stages in which the feed vto the initial stage comprises the propane oil andV sludge removed Vfrom the secondary stage. 4TheV feed to the secondary stage comprisesfresh acid andthe propane oil removed from the'initial stage. In the tertiary stage the acidsludge removed from the initial stageV is contacted with an additional volume of the' liquefied normally gaseous hydrocarbon solvent.

In order to further illustrate the invention, the following examples are given which should not be construed as limiting manner whatsoever:

Example 1 A petroleum oil boiling in the lubricating oil boiling range was deasphalted and dewaxed in' propane solution. The deasphalted and dewaxed oil was passed to an acid treating system in propane solution in which the ratio of oil to propane was approximately 1 to 4. The solution was contacted with 40 pounds per barrel of 80% sulfuric acid, based upon fthe propanefree oil. In this operation, approximately 25% of the propane-free oil was removed with the acid sludge from the separation zone. The acid sludge was removed from the separation zone and mixed with an additional volume of liquid propane in which the ratio of additional propane to sludge was approximately 1 to 0.75. Under these conditions, a substantial quantity of the oil was recovered from the acid sludge.

The quality of the recovered oil as compared with the acid treated oil is as follows:

From the above, it is apparent that the quality of the oil recovered from the sludge by the process of the present invention compares favorably with the acid-treated oil.

Example Z In one operation an acid sludge was treated with liquefied propane at a temperature of about 80 F. In another operation the temperature of treatment was about 100 F. The results of these operations were as follows:

Tempera- Operation ture of cglle treatment F. Per cent l 80 7.0 2 100 8. 8

the same in any 3. Improved process for the acid treatment of petroleum oils which comprises dissolving said petroleum oils in a liquefied normally gaseous hydrocarbon solvent, treating the solution with a mineral acid under conditions to form an acid sludge from said petroleum oil, removing said acid sludge and adding to said sludge an additional quantity of the liqueed normally gaseous hydrocarbon under conditions to form two phases, separating the liquefied normally gaseous hydrocarbon and recovering valuable oil constituents' therefrom.

4. Process as defined by claim 3, lin which said liquefied normally gaseous hydrocarbon comprises propane and in which said acid sludge is contacted at a temperature of about 100 F.

5. Process for the treatment of petroleum oils, which comprises dissolving said petroleum oil in a liquefied normally gaseous hydrocarbon solvent, treating the solution of petroleum oil in solvent in an initial stage with an acid sludge under conditions to form an acid phase and an oil phase, separating said acid phase and contacting the acid phase material with an additional quantity of the liquefied normally gaseous hydrocarbon solvent under conditions to form two phases, separating the liquefied normally gaseous hydrocarbon phase, and recovering valuable oil constituents therefrom, removing the oil phase from said initial stage and contacting the same in a secondary stage with fresh mineral acid, under conditions to form an acid sludge phase and an oil phase, removing said acid sludge phase and recycling the same to said initial stage, separating said oil phase from said secondary stage, and separating the liquefied normally gaseous hydrocarbon solvent therefrom.

6. Process as defined by claim 5, in which said liquefied normally ,gaseous hydrocarbon cornprises propane.

'7. Process as defined by claim 5,'in which said liquefied normally gaseous hydrocarbon solvent comprises propane and said mineral acid comprises a sulfuricv acid having a concentration in the range from about to about 100%.

8. A process for the treatment of petroleum oils comprising the steps in combination of mixing the petroleum oil with liquefied propane at a temperature near room temperature to produce an oil solution in propane, mixing the oil solution with sulfuric acid, settling the mixture to produce an acid sludge, separating the acid sludge substantially free from propane, and treating the propane-free sludge with a further quantity of liquefied propane to dissolve out from the sludge a further portion of petroleum lubricating oil.

9. A process for the treatment of petroleum oils comprising the steps in combination of mixing the petroleum oil with liquefied propane at a temperature near room temperature to produce an oil solution in propane, settling out from the mixture undesired asphaltic materials, mixing the oil solution with sulfuric acid, settling the mixture to produce an acid sludge, separating the acid sludge substantially free from propane, and treating the propane-free sludge with a further quantity of liquefied propane to dissolve out from the sludge a further portion of petroleum lubricating oil.

10. A process for the treatment of petroleum oils comprising the steps in combination of mixing the petroleum oil with liquefied pro-pane at a temperature near room temperature to produce an oil solution in propane, settling out and removing asphaltic, material vfrom the solution, chilling the 'solution ton crystallize kout fandV remove wax, mixing `theoil'solution with sulfuric acid, settling the mixture to produce. an acid sludge, separating the acid sludge substantially free from propane; and treating the propane-free sludge with a. further quantity of liquefied propane to dissolve Vout from the sludge 'a `further portion of petroleum lubricatingoil;Y Y -v 171. A process for the treatment Af petroleum oils comprising the steps in combination of mixing the petroleum oil with `liquefied propane at a temperature near room temperature to produce an oil solution in propane, mixing the oil solution with sulfuric acid, settling the mixture to produce an acid sludge, separating the acid sludge substantially free from propane, and

treating the propane-free sludge with a further quantity of liqueed propane to dissolve out from the sludge a further portion of petroleum lubricating oil, volatilizng out the propane from both propane solutions and combining the recovered oil to yield a larger proportion of high grade lubricant.

GEORGE S. BAYS, JR. 

